Yeah unfortunately geolocation isn't an exact science. For instance, living in Glasgow (Scotland, UK) I frequently find myself being geolocated to London (England, UK). This is because the company that owns the IP address I'm connected to, has its registered access in London.
Some IP address blocks are registered to a more local office, but unfortunately it's not always possible to be 100% accurate.
Then there's some IP addresses that flat out don't have a registered address, either because the registered address records are not public, or for some other reason unknown to me.
The mod tries, it really does. That's all you can ask of the lad
Fillip